Dry Cleaning Techniques · 2006-06-01 · Jong-Myoung Lee, Laser Engineering Group, IMT Co. Ltd....

세정기술워크숍

Dry Cleaning Techniques

Focused on Semiconductor & OLED applications

2006. 5

㈜ 아이엠티, 레이저그룹

이 종 명

www.imt-c.co.kr

http://www.imt-c.co.kr/

Jong-Myoung Lee, Laser Engineering Group, IMT Co. Ltd.

Dry Cleaning Techniques

Limits of wet cleaning> High aspect ratio structure (contact, trench)> Water mark> Corrosion issues (Cu, low-k)> Cluster tool> Environmental issues (water, chemicals)

Plasma cleaningDry ice cleaningAr aerosol cleaningUV lamp cleaningSuper critical fluid cleaningLaser cleaningLaser shock cleaningLaser plasma cleaning


Plasma cleaning (1)

Remote plasma cleaning> Ashing = PR stripping> in-situ etch/strip processingDirect plasma cleaning : Reactive plasma & Ar plasma> Ar plasma: pre-deposition cleaning by sputtering> Reactive plasma:

*PR Stripping mechanism

: chemical reactionO2 => O+O, H2O => 2H+OO + PR => H2O+CO+CO2 + …

chemical reaction=> volatile byproducts

ex) PCB flux cleaning,desmearing,deflashing

Plasma

Processchamber

Remote plasma chamber

Wafer

Heated plate

To the pump

Microwave

O2H2O

O OO

OO O O O

HHH H

H


Plasma cleaning (2)

*Unique Characteristics

>> Advantages: 1) In-situ dry cleaning2) No moisture effect => no

metal corrosion3) Good organic removal4) Surface activation =>

good bond ability

>> Disadvantages:1) poor inorganic & strong

PR residue removal2) Isotropic cleaning3) Plasma charging4) Non-feasible double-side

cleaning

Atmospheric Plasma cleaning> No vacuum> Conveyer system> Mass cleaning> Only flat surfaces

*Appl: FPD glass, pre-wiring & molding


Dry Ice cleaning (1)

Cryokinetic source: CO2

>> CO2 dry ice pellets>> Cleaning type1. Soft dry ice cleaning = CO2 snow cleaning

> liquid CO2 => adiabatic expansion at nozzle => dry ice generation and blowing

2. Hard dry ice cleaning = CO2 pellet cleaning> Dry ice lump => pellet => high pressure blasting


Dry Ice cleaning (2)

Source: KCTech

Cleaning mechanisms> Physical blasting> Thermal shock (-78.7C)> Sublimation expansion (x800)> CO2 solubility: organic removal

Applications> Pellet : semi. equipment surface cleaning (Komico)> Snow : FPD surface cleaning (KCTech)


Ar aerosol cleaning (1)

Cryokinetic source: ArAr / N2 mixture => compression => adiabatic expansion from the nozzle => Ar aerosol ejection

>> IBM patent technology => FSI International commercialized.

• Advantages1) Dry process2) Excellent particle removal performance

• Disadvantages1) Pattern damage => flat surface2) Thermal shock3) Expensive maintenance due to high purity Ar4) Expensive equipment due to Vacuum process


Ar aerosol cleaning (2)

Cleaning performance

Corrosion removal on Al line


UV lamp cleaning

UV radiation (Hg lamp) + O2 => O & O3 (O+O2)Mechanisms: Direct bond breaking + Chemical reactionE = hν = hc/λOrganic contamination removal (UV/O3 cleaning)Applications: PR hardening, OELD cleaning, surface activation

>> Competition with AP tech


Super critical fluid cleaning (1)

Super critical regionSCF characteristics (CO2)> High density (~liquid)> Low viscosity (~gas)> High diffusivity (~gas)> High solubility (CO2)> Easy recycling

Organic removal process> PR removal

Nano-scale pattern rinse & dry process> Deep penetration


Super critical fluid cleaning (2)

SCF Cleaning Demonstration

Source: K.T.Lee at Surface cleaning workshop, Boston

>> Co-solvent is essential to enhance the cleaning performance.


What is a laser cleaning?

Definition of laser cleaning: A process which removes contaminants from a surface by laser-surface interactions

Ref: 레이저와 청정가공,

이종명저, 한림원, 2002

Cleaning mechanisms1. Photo-thermal effect2. Photo-mechanical effect3. Photo-chemical effect


Process characteristics

Unique characteristics

- Precise process which ceases shortly after the laser pulse has ended

- Selective process which can be tuned for the removal of specific substances with a proper selection of wavelength

- Non-contact process which produces no contact wear

- Surface relief process without any mechanical loads

- Controllable process that a specific thickness of materials can be removed

- Environmentally preferable (or clean) process since it is a dry process


Artwork conservationFirst laser cleaning shoot at

1975, Venice


Medical applications***Applications: Dermatology & Dental Surgery


Industrial applications


Comparison of cleaning processes

Media blasting

Dry ice cleaning

Wet chemical cleaning

Laser cleaning

In-situ cleaning(op. Off-line)

No Yes No Yes

Labor required High Medium High Low

Level of automation Low Low Low High

Noise level Medium High Low Low

Substrate wear Yes No Medium No

Environmental hazards Medium Medium High Low

Post-cleaning waste High Low High Low


Summary

Every cleaning methodologies have their own advantages and drawbacks, so fundamental understanding of the cleaning processes is most important for successful applications.

Cleaning prospect (Semi. Industry)

> Wet & Batch => Hybrid => Dry & Single

Laser cleaning has unique characteristics and its industrial applications will be expand rapidly.

iMT holds diverse laser cleaning techniques and systems, i.e. LSC, LPC, SLC, LMC, ISM etc.

A creative idea from industrial fields is most important to implement the new technology successfully.

Dry Cleaning Techniques · 2006-06-01 · Jong-Myoung Lee, Laser Engineering Group, IMT Co. Ltd....

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